Juices, liquors, syrups, and/or molasses comprise a class of sugar-containing solutions which are produced during raw sugar manufacturing and sugar refining. Juice refers to the liquid part of a plant or fruit which is extracted for sugar recovery. Syrup is the term generally applied to liquid sugar solutions made by boiling or evaporating mixtures containing sugar and water, such as raw sugar juice or clarified raw sugar juice. The term liquor generally refers to partially concentrated sugar solutions and syrups generated during the raw sugar manufacturing and sugar refining processes.
Molasses is a dark brown sugar-containing composition which is generated during raw sugar manufacturing and sugar refining. The mixture of sugar and mother liquor discharged from the sugar boiling pan is called massecuite. In raw sugar practice the different grades of massecuites are given either letter (A, B, C) or number (1.sup.st, 2.sup.nd 3.sup.rd) designation. The mother liquor or molasses purged from the massecuites are given similar designations, (i.e., A massecuite yields A molasses). Refinery massecuites are usually named strikes and the mother liquor is refereed to as a syrup. Blackstrap or final molasses is the by- or end-product of raw sugar manufacturing and sugar refining. It is a viscous liquid which is separated from the final low grade massecuite. The sucrose present in blackstrap molasses cannot be crystallized therefrom by conventional methods.
A generalized analytical listing of the composition of juices, liquors, syrups, and/or molasses cannot be made because of the many variations in starting materials and manufacturing processes used to obtain or prepare these compositions. These variations include variety and maturity of starting material e.g., sugar cane, beet, etc., climate, soil condition, extent of milling, and clarification technique.
The primary components of interest to the present invention are always existent in juices, liquors, syrups, and/or molasses, and comprise the lower molecular weight components of these solutions which include sugars (sucrose, glucose, and fructose) and inorganic salts ("ash"). A secondary group of interest comprises the higher molecular weight components of juices, liquors, syrups, and/or molasses, and these include the organic non-sugars, nitrogenous compounds, non-nitrogenous acids, waxes, sterols, phosphatides, gums, starches, pentosans and vitamins. Various inorganic-organic complexes are present in this high molecular weight grouping as well. These high molecular weight components are usually present only in small amounts, such as a few percent by weight.
Process juices, liquors, syrups and/or molasses are a group of sucrose containing solutions that are produced during the various steps of raw sugar manufacturing and sugar refining. The higher molecular weight components present in these solutions tend to retard sucrose crystallization. Removal of the high molecular weight components is very desireable because it permits a higher recovery of sucrose from crystallization of the process solutions.
The sucrose present in blackstrap or final molasses is not recoverable by conventional techniques, although several processes for such recovery have been suggested. These are generally referred to as "de-sugarization" processes, and the most attractive of them requires pre-treatment of the molasses followed by ion exclusion chromatography to separate the sucrose from the non-sucrose impurities.
One such de-sugarization process is used in the processing of beet molasses. In this process beet molasses is pre-treated to reduce the calcium ion concentration therein, then processed by ion exclusion chromatography to separate the sucrose from the non-sucrose components. The resulting sugar-rich fraction is evaporated and the sucrose crystallized therefrom.
A major drawback to the proposed desugarization processes, particularly when applied to de-sugarize molasses derived from cane sugar processing, results from fouling of the ion exclusion resin due to blockage of the resin pores by the higher molecular molasses components. This fouling results in the need for frequent regeneration or replacement of the chromatographic resins, a requirement which significantly increases processing costs to an unacceptable level.
It is known in U.S. Pat. No. 4,104,078, hereby incorporated by reference, in toto, to separate dextrans in carrier solvents (70-95% solvent) by a chromatographic method involving a sequential valve operation. Other U.S. Patents of interest involving chromatographic or related separations are U.S. Pat. Nos. 4,257,884, 4,717,425, 4,379,751 and 4,363,672, all hereby incorporated by reference.
Accordingly, it is an object of the present invention to provide an effective method for separating the lower molecular weight sugars from the higher molecular weight non-sugar impurities of juices, liquors, syrups and, particularly, molasses, which process may be economically employed on a commercial scale to achieve increased recovery of sugar. This is achieved by increasing sugar recovery from the feed of juices, liquors, syrups, molasses or mixtures of them by removal of the higher molecular weight non-sugar impurities which in turn permits further processing of the lower molecular weight fraction by ion exclusion chromatography, ion exchange chromatography and/or crystallization to produce a natural sweetener product for use in the food, pharmaceutical, dairy and bottling industries.